SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c26f5c8f51af7abfa8e3690daa1e4a77be10966aeef81a4657060b003dd0c7fa' 
  AND token = 'a9C7SNLIF4gX49lrCDyZ1IrmI9MCl1QFbiI5fcSYRVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}